Visual display devices are well known and include cinematic film projectors, television sets, monitors, plasma displays, liquid crystal display (LCD) televisions, and projectors etc. Such devices are often employed to present images or image sequences to a viewer. In the 1960s, backlighting was introduced due to the fact that televisions required a “darker” room for optimal viewing. Backlighting is in its simplest form white light, emitted from e.g. a light bulb, projected on a surface behind the visual display device. Backlighting has been suggested to be used to relax the iris and reduce eye strain. During recent years the backlighting technology has become more sophisticated and there are several display devices on the market with integrated backlighting features that enables emitting colors with different brightness depending on the visual information presented on the display device. The benefits of backlighting in general includes: a deeper and more immersive viewing experience, improved color, contrast and detail for best picture quality, and reduced eye strain for more relaxed viewing.
EP 1551 178 A1 discloses a supplementary visual display system for use in conjunction with a display device including an image display region for presenting images to a viewer. The display system comprises one or more illumination sources that at least partially peripherally surround the image display region. This system, and other systems of the prior art, are developed for operating the supplementary visual display system in an active mode, i.e. when images are presented on the screen of the display device.
The inventors of the present invention have appreciated that an improved visual display system which may be used in an off-state of the display device would be of benefit, and have in consequence devised the present invention.